I wanted to brew my first 10 gallon batch tommorow and I am having 2nd thoughts. I already milled my grain at the LHBS for a 10 gallon batch. Can I mix the grain well enough to split this into two 5 gallon batches, or would you not take the chance?
My concerns of not doing a 10 gallon batch is not being able to cool the wort ( I have a small copper IC) and not being able to heat the wort to boiling (I have a keggle and a turkey fryer burner IBU ?)

I dont think it is possible to seperate the grains in half, you will have a lot more crystal etc. in one batch and not enough in the other, do you have a submersible pond pump? If so you should be able to cool the wort by running ice water through the chiller, as for the boil, I think it will work, just might take a bit longer to get the boil going, good luck.

If you're ever going to be able to cool a 10 gal batch with a small IC, it will be during winter when your tap water is cold. However, a rubbermaid tub, two bags of ice and a submersible pump go a long way all year round.

I would bet the IC will be fine. My chiller with tap water will get it down to about 80 in about 7 minutes. I do have a 50 IC in a keggle with 5 gallons of wort but half of my IC is about the wort anyway.

Use the tap water to get it down as low as possible and then switch to a cooler and pump with ice water if you have the capability.